Conditioning equipment for the copy paper supply in copying machines

ABSTRACT

A machine of the photoelectrostatic copying-type, including a relatively small, confined chamber in which photoconductive sheet material is placed for automatic feeding into the machine. A system is provided for conditioning the atmosphere in the chamber to maintain it at a predetermined level of relative humidity to keep the photoconductive material from becoming distorted and damaged.

United States Patent [72] Inventors Joseph A. Verderber [56] References Cited Lyndhursl; UNITED STATES PATENTS James A- Fortcamp, 2 l h I I 33: Bmdview 3,113,003 12/1963 Teiser et al. 34/50 3,349,22I I0 1967 S h l t I 355 3X 21 Appl. No. 863,070 l c 26 e a 22 Fi| d Oct 2, 1969 Primary Examiner-Samuel S. Matthews Patented Jan. 11, 1972 Assistant Examiner-Richard L. Moses [73] Assignee Addressograph-Multlgraph Corporation Attorneys-Russell Root and R y y Cleveland, Ohio 7 [54] CONDITIONING EQUIPMENT FOR THE COPY l la i Ei MACHINES ABSTRACT: A machine of the photoelectrostatic copyingaims raw type, including a relatively small, confined chamber in which [52] U.S. CI 355/3, photoconductive sheet material is placed for automatic feed- 34/46, 34/50 ing into the machine. A system is provided for conditioning [5 I] Int. Cl ..G03b 27/00 the atmosphere in the chamber to maintain it at a predeter- Field of Search 355/3; mined level of relative humidity to keep the photoconductive 34/46, 50; 219/362 material from becoming distorted and damaged.

) t he 6 .4 I 68 7 /4 6 1/ a4 52 z i a 2e 7g 6 Z2 Z6 Z0 MACHINE OPERATlNG CONDITIONING EQUIPMENT FOR THE COPY PAPER SUPPLY IN COPYING MACHINES Photoelectrostatic copying machines use a specially treated paper having a layer of photoconductive material such as zinc oxide in a resin binder. The character of the paper is such that its exposed surfaces are usually substantially impervious to moisture. However, moisture can pass gradually through the cut edges of the sheets into and out of the paper. For this reason, the photoconductive paper is cut and packaged in a controlled environment or atmosphere, including a relative humidity of between about 42 to about 45 percent. Further, the paper is packaged in plastic bags or other containers which are relatively moistureproof. Therefore, there is generally no problem in transporting or shipping the paper to the consumer. A problem can arise, however, when the seal of the package is broken, since too much or too little moisture in the paper may impair or destroy its usefulness.

The moisture content of the paper is important in several respects. For one thing it governs the electrical resistivity of the paper. In other words, the moisture content affects the papers ability to accept an electrostatic charge. This is important in an electrophotographic reproduction process, which essentially comprises charging the paper to make it photosensitive, exposing the sensitized paper to an image, and developing the image on the paper. The quality of the reproduced image is largely dependent on the electrostatic charge accepted by the paper.

In atmospheres of low relative humidity, the moisture content may decrease to a level where portions of the paper sheet cannot readily dissipate its electrostatic charge in response to illumination. The resulting copies are apt to have excessive and irregular toning in the background areas. Conversely, in atmospheres of high relative humidity, the electrical resistivity in portions of the sheet may fall to a level where, for example, the papers lateral conductivity becomes too great in relation to the face-to-face conductivity. In such cases, the electrostatic image charges cannot be suitably localized, and the resulting images may be weak, distorted or fail to appear.

Improper moisture content in either direction also can cause the paper to curl at the edges. The paper becomes sufficiently wavy and distorted to be unsuitable for feeding into the machine. Such paper must be discarded or rehabilitated to its flat, undistorted condition.

The aforementioned problems are perhaps even more acute in electrostatic copying machines designed for producing masters, i.e., photocopies from which other copies are printed, mainly because masters are not made at the same rate that normal copies are produced.

It is not uncommon for masters to be made one at a time. Furthermore, master sheets are of different size which frequently necessitates storing opened packs of unused sheets of differently sized paper for extended periods of time.

Notwithstanding the unpredictable character of electrostatic paper sheets due to their moisture impervious coatings and moisture receptivity at their cut edges, and notwithstanding the considerations of size and cost normally associated with the employment of humidity control equipment for overcoming severely abnormal ambient humidity conditions, it has been found that the paper can be made to remain flat and undistorted, and to retain proper electrical characteristics if it is stored and used in a controlled atmosphere having a relative humidity in the range of from about to about 55 percent, and preferably in the range of from about 40 to about 50 percent and that this is a feasible procedure in direct association with the copying machine itself in spite of the size, power and cost limitations which are inherent in such a device.

Attempts have been made to regulate the relative humidity of the atmosphere in which the paper is sued. For example, US. Pat. No. 3,349,221, describes a copier with an electrically operated blanket heater disposed in the feed chamber for keeping paper in condition in climates where the ambient atmosphere is normally excessively humid. While this device is eminently successful in its assigned task, no provision is made for handling the situation which arises when the ambient atmosphere is unusually dry. The invention hereinafter described is directed to providing a system for automatically regulating the relative humidity to maintain it in the ranges indicated above regardless of the surroundings in which the copying machine is placed.

Briefly stated, the invention is in a photoelectrostatic copying machine using photoconductive paper. The machine is provided with a relatively small, confined chamber in which the paper is placed for automatic feeding into the machine. The term confined chamber as herein used, means a chamber of such size that the relative humidity of the atmosphere within the chamber can be effectively controlled on a practical and economically feasible basis. It is not essential and usually not desirable that the confined chamber be completely sealed from the ambient atmosphere. There can be some leakage of air so long as it is on a restricted bases not detrimental to maintaining the relative humidity within the range indicated above. A heater is disposed in the chamber for lowering the relative humidity in the atmosphere of the chamber, and a humidifier and blower are used for adding moisture to the atmosphere of the chamber. Suitable control means are tied into both of these agencies in a novel manner so that the appropriate one is brought into play when needed to bring the relative humidity of the atmosphere in the chamber within the acceptable range.

Stated in another way, it has been a matter of general knowledge in the art that the coatings used on photoelectrostatic paper are of a highly moisture resistant character, and that intentionally changing the moisture content in the body stock of such coated sheets by artificial means is an exceedingly difficult and complex matter involving strongly overcorrecting the ambient humidity condition for an extended period of time. ln-accordance with this invention it has been found possible, nevertheless, to maintain photoelectro static sheets in their initial prime condition at all times by placing them in a closed off but not necessarily sealed storage area of a particular size on the copying machine itself and associating such storage area with automatically controlled humidity adjusting equipment also on the copying machine and of size and power ratings small enough to be suited ideally to the size, price range and power limitation of an office copying machine. Moreover, this result can be accomplished by the present invention whether the machine is subjected to ambient humidity conditions which are either too moist or too dry, by means which will automatically compensate whichever situation is being encountered at the time.

The following description of the invention will be better understood by having reference to the annexed drawing, the single FIGURE of which is a cross section of a paper storage and feed chamber associated with a copying machine in accordance with the present invention, a schematic showing of the wiring connections being associated therewith.

Referring to the drawing, there is shown a fragment of photoelectrostatic type copying machine, generally indicated at 10, for making masters from which other copies are reproduced. The machine 10 comprises a relatively small, confined chamber 12 in which photoconductive paper is placed for feeding into the balance of the machine 10. The chamber may encompass, for example, about 3 cubic feet of air or less.

The confined chamber 12 is rendered accessible by a cover 14 which is pivotally mounted on the machine 10 by a hinge 16. A seal 18 of resilient material is disposed along the lower lip 20 of the cover 14, for sealing engagement with the margin of the opening of chamber 12. The, seal 18 also acts to eliminate contact noise which might be associated with closing the cover 14.

A plurality of storage shelves 22 and 24 are provided in the feed chamber 12. The shelves 22 and 24 are especially useful for storing partially used packs of differently sized sheets of paper, since it is often necessary to change the size of paper to make different masters of different sizes. These shelves make excellent storage bins for opened packages of paper which otherwise would have to be stored outside the machine so as to be subject to deterioration.

A pack of paper of the size desired is placed on the upper surface of a feed guide 26 for feeding into the machine 10. The shelves 22 and 24 and feed guide 26 are preferably parallel and angularly disposed to the horizontal for convenient location and handling of the paper. The confined chamber 12 is provided with a restricted opening 27 through which paper passes into the machine 10.

An automatic feeding mechanism, generally indicated at 28, is disposed in close proximity to the restricted opening 27 and is operatively associated with the feed chamber 12 for successively taking the uppermost sheet of paper from a pack of paper disposed on the support surface 26, and moving the sheet through opposing feed rollers 30 and 32 which are disposed in the restricted opening 27 and substantially fill it to prevent other than very nominal passage of air between the feed chamber 12 and balance of the machine 10.

A heater 34 is mounted on a wall of the chamber 12 in a position to heat the air in the chamber. The heater 34 can be of any suitable design. For example, an electric heating pad similar to the electrically responsive heating element encased in electrical insulating material described in U.S. Pat. No. 3,349,22 l will serve effectively.

There is also provided humidifier 40 which is disposed in air communicating relation with the feed chamber 12 through outlet and inlet pipes 42 and 44, respectively, which are secured to outlet and inlet ports 46 and 48 in the wall of the feed chamber 12.

The humidifier 40 can be of any suitable design which does not significantly raise the temperature of the atmosphere in the confined chamber 12. For example, humidifiers which mechanically disperse droplets of moisture into the air, and those employing moisture-pervious plates and grilles over which air is passed, are well suited for conditioning the atmosphere in the confined chamber 12. For the purposes of this description the type of humidifier contemplated will be referred to as a heatless vapor generating humidifier to distinguish from steam generators which have been tried in the circumstances without noticeable effect.

A conventionally designed blower 50 is interposed between the outlet pipe 42 and humidifier 40 for circulating air from the feed chamber 12, through the humidifier 40 where the air is moisturized, and back into the feed chamber 12 via pipe 44. The blower is powered by a suitable electric motor 51.

Humidity sensitive control means are provided for regulating the operation of the heater 34 and the humidifier 40 to maintain the relative humidity within the chamber 12 at a value within the appropriate range.

In the preferred form of the invention this control means takes the form of a pair of humidistats 36 and 52 mounted within the chamber 12. The former is so arranged as to control energization of the circuit of the heater 34, and the latter controls the power to the motor of blower 50. The humidistats 36 and 52 jointly cooperate to provide a humidity control means for monitoring the operation of the heater 34 and the humidifier 40, so as to maintain the relative humidity in the chamber 12 within the desired range of between about to about 55 percent, and preferably in the range of about to about percent whether the ambient humidity is high or low. For example, whenever the relative humidity of the atmosphere of the feed chamber 12 rises above the maximum desired level, the humidistat 36 would respond to activate operation of the heater 34 to heat the air and increase moisture holding capacity to a point where the relative humidity is lowered and is again within the desired range. Alternatively, where there is insufficient moisture in the atmosphere of the feed chamber 12, and the relative humidity falls below a minimum desired level, the humidistat 52 would respond to activate operation of the blower 50 to put more moisture into the atmosphere and return the relative humidity to a value within the desired range.

One of the features of the invention is associated with a particular characteristic of the operating mechanisms of the conventionally designed humidistats 36 and 52. The construction is such that there is perhaps a 5 percent differential between the relative humidities at which the heater or humidifier will start to function and the relative humidity at which the heater or humidifier will start to function and the relative humidity at which it will cease functioning. For example, the heater 34 might start operating when the relative humidity rises above 50 percent, and will continue functioning until the relative humidity drops to perhaps 45 percent. Similarly, the humidifier 40 will begin operating when the relative humidity falls below about 40 percent, for example, and may continue functioning until the relative humidity rises to perhaps 45 percent. This prevents any rapid oscillation between on and off condition of the heater or humidifier, whichever is the primarily active agent under any particular prevailing humidity conditions, and thus provides relatively stable operating conditions.

A single control using a single humidity responsive element could be designed, which would maintain the relative humidity in the above range, and this could be used in place of the separate humidistats 36 and 52. The presently described arrangement, however, makes it possible to take advantage of price savings and convenience attendant upon using conventional humidistats presently on the market, and is accordingly preferred.

One example of a wiring scheme for rendering the controls operative is shown in the drawing in which the power supply mains, normally operating at 1 10 volts AC, are designated L and L The line L is connected to one side of each of the thermostatic switches 36 and 52 by leads 60 and 62 respectively, and finally to one terminal of the blower motor 51. Line L is connected by a lead 64 to one terminal of the heater 34, the other heater terminal being joined to the second terminal of thennostatic switch 36 by a lead 66. The line L leads thence to the other terminal of blower motor 51. A relay 68 controls the operation of motor 51 and its switch contacts are arranged to make or break the connection of the line L with the second motor terminal. Control the relay by thermostatic switch 52 is effected by reason of a lead 70 which connects the second terminal of the thermostat 52 with one terminal of the coil of relay 68, the other terminal ofwhich is tied into the line L by a lead 72.

It is important to note that the size of the chamber 12 must be kept to a minimum, preferably not in excess of about 3 cubic feet, inasmuch as an air volume in the chamber in excess of this amount would make maintenance of humidity conditions much more difficult, and hence could possibly involve the use ofequipment whose size and cost would be out of scale with the size and cost of the usual copying machine, so as to render the combination of the present invention impractical. For the same reasons, unnecessary leakage area should be held to a minimum, with the openings normally being confined substantially to those necessitated by the feedout equipment and having a total distributed leakage area of not more than about 4 or 5 square inches and preferably less. It will also be noted that this leakage are is not concentrated in one place but is widely distributed across the lengths of the feed rolls so that orifice width is quite reduced and resistance to air exchange thereby increased with little tendency to compromise the humidity condition established within the chamber 12.

As example of the surprisingly low capacity and small power requirements of the equipment which can be used for successfully carrying out this invention, it may be observed that for a chamber of about 3 cubic feet as described in the foregoing paragraph experience has shown that ample capacity is provided by a heating pad rated at 55 watts, and by a humidifier of the mechanical dispersion type whose impeller motor power rating is about 60 watts and which is capable of dispersing about i /z-pints of water per hour. In place of the mechanical dispersion humidifier it has also been found effective to use an evaporation humidifier employing 10 porous plates, each 6X6 inches, and having a blower motor rated at 26 watts.

Another feature of the present invention involves the manner in which the power control for the equipment which controls the humidity in the chamber 12 is related to the power control for the balance of the machine circuits.

As seen in the drawing, power lines L and L lead directly to a connector or plug 74 which can be inserted in the usual wall outlet. Branching conductors L and L lead to the other electrical circuits of the machine indicated generally at 76, and are controlled by a master on-off switch 78. With the arrangement as disclosed, the operator can turn the machine on or off at will, and this action will have no effect upon the apparatus for maintaining proper atmospheric conditions in chamber 12. If the operator desires to deenergize the humidity controlling features, he must withdraw the connector 74 from its wall receptacle, requiring special thought and attention on his part. Thus the likelihood that the operator will inadvertently disable the humidity maintaining facilities when he merely intends to terminate machine operation is reduced to a minimum.

While the foregoing description has been couched in terms of an electrostatic copying machine of the type using photoconductive paper as the copy sheet, it will, of course, be understood that the principles may be applied to other office machines of the copying and duplicating class. For example, in some cases an electrostatic copier of the transfer type may employ a humidity-sensitive photoconductive element as a part of the machine, and in such cases it is possible to insure proper operation thereof regardless of unsuitable humidity conditions by enclosing the humidity-sensitive photoconductive machine part in a confined chamber, similar to chamber 12, suitably mounted on the machine.

Again, plain bond paper such as that used as copy paper on transfer type electrostatic copiers or on lithographic duplicators may become degraded by being subjected to excessive humidity deviations, and consequently fail to feed and handle well on the machine. This situation can be avoided by enclosing the storage area for the plain copy paper, or a feed station through which it passes, in a confined chamber similar to chamber 12 suitably arranged on the machine.

In other words it has been discovered that any part of such an office duplicating or copying machine, or any store of a supply item used with the machine, which part or supply item is subject to deterioration as a result of excessive humidity deviations, can be protected by a chamber on the machine, the internal atmosphere of such chamber being controlled by agencies suited to mounting directly on the office machine.

Although the preferred embodiment is described as including both a heater and a humidifying means, it will be appreciated that in special situations where the ambient atmosphere is normally very dry, a chamber employing the humidifying means alone can prove fully effective, and the invention contemplates this situation as well as the combined arrangement disclosed in detail.

Thus, there has been provided a novel system for conditioning the atmosphere within a relatively small, confined chamber for holding photoconductive or photosensitive paper used or other humidity-sensitive material or part in an electrostatic copying or other office machine, which, irrespective of the apparently overriding size, cost, and power restrictions normally associated with such equipment, has been shown to be fully effective in maintaining the part in usable condition regardless of the extremes of humidity found in the ambient atmosphere.

What is claimed is:

l. A copying machine using photosensitive sheet material, comprising in combination:

a. a confined chamber for receiving and storing sheets of photosensitive material, the chamber including inlet and outlet ports in spaced relation;

b. means operatively connected to the chamber for feeding photosensitive sheets, one by one, from the chamber into the machine; means including a general operating circuit for making copies on the sheets as they issue, one by one, from the chamber;

d. humidity adjusting means comprising:

1. a heater disposed in the chamber for heating the atmosphere therein to reduce the relative humidity;

2. hollow conduit means connecting the inlet and outlet ports, and disposed outside the chamber;

3. a heatless, vapor generating humidifier interposed in the conduit means in air communicating relation with the chamber, for adding moisture to the atmosphere in the chamber;

e. means responsive to the relative humidity of the atmosphere in the chamber for controlling operation of the heater and humidifier to maintain the relative humidity in the chamber within a predetermined optimum range, said controlling means being constructed and arranged to activate the heater at a predetermined humidity level defining an upper margin of said optimum range, and activating the humidifier at a predetermined humidity level defining a lower margin of said optimum range, and terminating the operation of the heater or humidifier only after the humidity level has significantly overrun the respective margin to place the humidity level well within the optimum range; and

f. power connections for the machine providing branching circuitry supplying power to said general operating circuit via an on-offswitch, and to said humidity adjusting means and said control means by direct conductors bypassing said switch, whereby the operating or idle condition of the copying machine can be set without danger of disturbing the power to the humidity adjusting means and control means.

2. in a machine of the class of copying and duplicating machines embodying a part or using supplies which tend to deteriorate in response to deviation of humidity conditions from a predetermined optimum range and having a general operatingcircuit which is switched on and off as the machine is to be used or left idle, the improvement comprising:

a. a housing constituting an element of the machine, at least a portion of said housing constituting a chamber embracing said humidity-sensitive part or a store ofsaid humidity sensitive supplies, and being constructed and arranged to inhibit rapid air exchange between said chamber and the ambient atmosphere whether the machine is operating or not;

b. controllable humidity adjusting means mounted on the machine frame and operable to adjust the relative humidity in said chamber;

c. means responsive to the relative humidity of the atmosphere in the chamber for controlling operation of the humidity adjusting means to keep the relative humidity in the chamber at values within said predetermined optimum range, said controlling means being constructed and arranged to activate the humidity adjusting means at a predetermined humidity level defining a margin of said optimum range and terminating the operation thereof only after the humidity level has significantly overrun said margin to place the humidity level well within the op timum range;

d. main on-off switch means for controlling said general operating circuit; and

e. power connections for the machine providing branching circuitry supplying power to said general operating circuitry via said on-off switch, and to said humidity adjusting means and said control means by direct conductors bypassing said switch, whereby the operating or idle condition of the machine can be set without danger of disturbing the power to the humidity adjusting means and the control means. 

1. A copying machine using photosensitive sheet material, comprising in combination: a. a confined chamber for receiving and storing sheets of photosensitive material, the chamber including inlet and outlet ports in spaced relation; b. means operatively connected to the chamber for feeding photosensitive sheets, one by one, from the chamber into the machine; c. means including a general operating circuit for making copies on the sheets as they issue, one by one, from the chamber; d. humidity adjusting means comprising:
 1. a heater disposed in the chamber for heating the atmosphere therein to reduce the relative humidity;
 2. hollow conduit means connecting the inlet and outlet ports, and disposed outside the chamber;
 3. a heatless, vapor generating humidifier interposed in the conduit means in air communicating relation with the chamber, for adding moisture to the atmosphere in the chamber; e. means responsive to the relative humidity of the atmosphere in the chamber for controlling operation of the heater and humidifier to maintain the relative humidity in the chamber within a predetermined optimum range, said controlling means being constructed and arranged to activate the heater at a predetermined humidity level defining an upper margin of said optimum range, and activating the humidifier at a predetermined humidity level defining a lower margin of said optimum range, and terminating the operation of the heater or humidifier only after the humidity level has significantly overrun the respective margin to place the humidity level well within the optimum range; and f. power connections for the machine providing branching circuitry supplying power to said general operating circuit via an on-off switch, and to said humidity adjusting means and said control means by direct conductors bypassing said switch, whereby the operating or idle condition of the copying machine can be set without danger of disturbing the power to the humidity adjusting means and control means.
 2. hollow conduit means connecting the inlet and outlet ports, and disposed outside the chamber;
 2. In a machine of the class of copying and duplicating machines embodYing a part or using supplies which tend to deteriorate in response to deviation of humidity conditions from a predetermined optimum range and having a general operating circuit which is switched on and off as the machine is to be used or left idle, the improvement comprising: a. a housing constituting an element of the machine, at least a portion of said housing constituting a chamber embracing said humidity-sensitive part or a store of said humidity sensitive supplies, and being constructed and arranged to inhibit rapid air exchange between said chamber and the ambient atmosphere whether the machine is operating or not; b. controllable humidity adjusting means mounted on the machine frame and operable to adjust the relative humidity in said chamber; c. means responsive to the relative humidity of the atmosphere in the chamber for controlling operation of the humidity adjusting means to keep the relative humidity in the chamber at values within said predetermined optimum range, said controlling means being constructed and arranged to activate the humidity adjusting means at a predetermined humidity level defining a margin of said optimum range and terminating the operation thereof only after the humidity level has significantly overrun said margin to place the humidity level well within the optimum range; d. main on-off switch means for controlling said general operating circuit; and e. power connections for the machine providing branching circuitry supplying power to said general operating circuitry via said on-off switch, and to said humidity adjusting means and said control means by direct conductors bypassing said switch, whereby the operating or idle condition of the machine can be set without danger of disturbing the power to the humidity adjusting means and the control means.
 3. a heatless, vapor generating humidifier interposed in the conduit means in air communicating relation with the chamber, for adding moisture to the atmosphere in the chamber; e. means responsive to the relative humidity of the atmosphere in the chamber for controlling operation of the heater and humidifier to maintain the relative humidity in the chamber within a predetermined optimum range, said controlling means being constructed and arranged to activate the heater at a predetermined humidity level defining an upper margin of said optimum range, and activating the humidifier at a predetermined humidity level defining a lower margin of said optimum range, and terminating the operation of the heater or humidifier only after the humidity level has significantly overrun the respective margin to place the humidity level well within the optimum range; and f. power connections for the machine providing branching circuitry supplying power to said general operating circuit via an on-off switch, and to said humidity adjusting means and said control means by direct conductors bypassing said switch, whereby the operating or idle condition of the copying machine can be set without danger of disturbing the power to the humidity adjusting means and control means. 